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1) Normal parents have a Tay-Sachs child. Tay-Sachs is a recessive condition. What is
the probability that their next child will be normal?
a. 1.0 (100%)
b. 0.25 (25%)
c. 0.75 (75%)
d. 0.00 (0%)
e. 0.67 (67%)
2) If you have a dominant disorder in a diploid organism, what two genotypes would
express the same phenotype?
a. homozygous dominant and homozygous recessive
b. homozygous dominant and heterozygous
c. homozygous recessive and heterozygous
3) If a home garden is planted with all heterozygous round peas, what proportions
would be observed in the progeny? (The wrinkled trait is recessive.)
a. all wrinkled
b. all round
c. 1/4 round and 3/4 wrinkled
d. 2/4 round and 2/4 wrinkled
e. 3/4 round and 1/4 wrinkled
4) A pea plant that is heterozygous for the dwarf gene (Dd) will be __.
a. tall
b. short
c. intermediate in height
d. extra tall
e. dead
5) A plant that has the genotype DD is said to be __.
a. heterozygous
b. homozygous
c. haploid
d. polyploid
e. mutant
6) A plant with the genotype Dd will produce gametes containing which alleles?
a. d only
b. D only
c. DD only
d. DD, Dd, and Dd gametes
e. D or d
7) If a plant that is heterozygous for purple flowers is crossed with a plant that is white,
what proportion of the progeny will have white flowers? (Purple is dominant.)
a. none
b. 25%
c. 50%
d. 75%
e. 100%
8) A test cross is designed to determine the genotype of a parent with the dominant
phenotype. A test cross produces progeny that are 1⁄2 tall and 1⁄2 dwarf. What is the
genotype of the tall parent?
a. Dd
b. DD
c. dd
d. D
e. d
9) In the F1 dihybrid cross (WwGg X WwGg), what is the probability of obtaining an
individual that is round, green, and true-breeding? (G = Yellow seed, g = green seed; W
= round seed, w = wrinkled)
a. 1/16
b. 3/16
c. 1/4
d. 1/2
e. 9/16
10) A pea plant that is true breeding (homozygous) for green round seeds is crossed
with a plant that has yellow wrinkled seeds. The F1 progeny all have round green seeds.
Predict the results of crossing the F1 plants with a homozygous recessive plant.
a. 1:1:1:1
b. 9:3:3:1
c. 1:0:0:0
d. 1:3:1:3
e. 1:2:0:0
11) A mother who is blood type AB has a child who is AB also. A potential father is
blood type O. A well-informed geneticist concludes that __________.
a. he cannot be the father
b. he is very likely to be the father
c. he or any other male of blood type O could be the father
d. no conclusion can be drawn
12) Flower color in snapdragons shows incomplete dominance. What phenotypes and
phenotypic ratios would you expect in a test cross of a pink flowered (RW) and a red
flowered (RR) snapdragon?
a. 3 red: 1 pink
b. 3 pink: 1 red
c. 1 white: 2 pink: 1 red
d. 1 red : 1 pink
e. 2 pink: 1 red
13) In a paternity suit a man disputes that he is the parent of a child although the mother
of the child says that he is. The man has type O blood. The child also has type O blood,
and her mother has type B blood. Could he be the father?
a. no, because type O is only found in homozygotes
b. no, because B is dominant to O
c. yes, because the mother could be heterozygous
d. yes, because the allele for type O is dominant
e. can't determine if he might or might not be
14) A female is heterozygous for the recessive X-linked gene for Lesch-Nyhan
syndrome, a recessive gene that leads to mental retardation, self mutilation, and early
death. What proportion of her daughters will be "carriers" for the trait?
a. 0%
b. 25%
c. 50%
d. 75%
e. 90%
15) In a paternity suit, a type AB woman named two men as possible fathers of her type
B child. One man was type AB, one type A. Which could have been the father?
A) AB
B) A
C) both of these choices
D) neither of these choices
16) A man and a woman both have normal color vision, but their daughter has redgreen color-blindness, a sex-linked recessive trait. The man sues his wife for divorce on
the ground of infidelity? Can genetics provide evidence supporting the case? Prove
your answer.
Assigned Practice Questions in Textbook
#s = 1, 3, 4, 5, 6, 8, 11